Validation of adhesion characterization methods for antistick coatings applied in cooking systems

Abstract

This study aims to validate an effective methodological analysis for the characterization of the adhesion values of antistick coatings employed in cooking systems. The morphology and chemistry of four different industrial products were investigated by roughness measurements, electron microscopy observations and infrared spectroscopy analysis. The adhesion of the coatings was evaluated comparing various techniques, such as the surface contact angle measurements, the pull-off test and the single lap-joint tensile shear method, in synergy with degradation phenomena simulated by P.E.I. abrasion and dishwashing tests. The single lap-joint tensile shear test was able to evaluate evident differences between all the proposed coatings, regardless of their state of deterioration, featuring the best selectivity among the used methods. However, the pull-off test proved to be a viable and more economical alternative for fast evaluation techniques, considering the overall instrument costs. While all the polytetrafluoroethylene-based systems turned out to be totally uninfluenced by the chemical attacks performed during the dishwasher cycles, the sol–gel coating exhibited lower performances of the applied releasing agent, before and after the mechanical degradation tests. Therefore, sol–gel coatings, despite being proposed as valid alternatives to PTFE ones, do not achieve the same quality standards in terms of releasing properties, being in addition much more sensible to degradation and loss in performances.